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      1 /*
      2  * libjingle
      3  * Copyright 2004 Google Inc.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions are met:
      7  *
      8  *  1. Redistributions of source code must retain the above copyright notice,
      9  *     this list of conditions and the following disclaimer.
     10  *  2. Redistributions in binary form must reproduce the above copyright notice,
     11  *     this list of conditions and the following disclaimer in the documentation
     12  *     and/or other materials provided with the distribution.
     13  *  3. The name of the author may not be used to endorse or promote products
     14  *     derived from this software without specific prior written permission.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
     17  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
     18  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
     19  * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     20  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     21  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
     22  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
     23  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
     24  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
     25  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     26  */
     27 
     28 #include "talk/session/media/rtcpmuxfilter.h"
     29 
     30 #include "webrtc/base/logging.h"
     31 
     32 namespace cricket {
     33 
     34 RtcpMuxFilter::RtcpMuxFilter() : state_(ST_INIT), offer_enable_(false) {
     35 }
     36 
     37 bool RtcpMuxFilter::IsActive() const {
     38   return state_ == ST_SENTPRANSWER ||
     39          state_ == ST_RECEIVEDPRANSWER ||
     40          state_ == ST_ACTIVE;
     41 }
     42 
     43 void RtcpMuxFilter::SetActive() {
     44   state_ = ST_ACTIVE;
     45 }
     46 
     47 bool RtcpMuxFilter::SetOffer(bool offer_enable, ContentSource src) {
     48   if (state_ == ST_ACTIVE) {
     49     // Fail if we try to deactivate and no-op if we try and activate.
     50     return offer_enable;
     51   }
     52 
     53   if (!ExpectOffer(offer_enable, src)) {
     54     LOG(LS_ERROR) << "Invalid state for change of RTCP mux offer";
     55     return false;
     56   }
     57 
     58   offer_enable_ = offer_enable;
     59   state_ = (src == CS_LOCAL) ? ST_SENTOFFER : ST_RECEIVEDOFFER;
     60   return true;
     61 }
     62 
     63 bool RtcpMuxFilter::SetProvisionalAnswer(bool answer_enable,
     64                                          ContentSource src) {
     65   if (state_ == ST_ACTIVE) {
     66     // Fail if we try to deactivate and no-op if we try and activate.
     67     return answer_enable;
     68   }
     69 
     70   if (!ExpectAnswer(src)) {
     71     LOG(LS_ERROR) << "Invalid state for RTCP mux provisional answer";
     72     return false;
     73   }
     74 
     75   if (offer_enable_) {
     76     if (answer_enable) {
     77       if (src == CS_REMOTE)
     78         state_ = ST_RECEIVEDPRANSWER;
     79       else  // CS_LOCAL
     80         state_ = ST_SENTPRANSWER;
     81     } else {
     82       // The provisional answer doesn't want to use RTCP mux.
     83       // Go back to the original state after the offer was set and wait for next
     84       // provisional or final answer.
     85       if (src == CS_REMOTE)
     86         state_ = ST_SENTOFFER;
     87       else  // CS_LOCAL
     88         state_ = ST_RECEIVEDOFFER;
     89     }
     90   } else if (answer_enable) {
     91     // If the offer didn't specify RTCP mux, the answer shouldn't either.
     92     LOG(LS_WARNING) << "Invalid parameters in RTCP mux provisional answer";
     93     return false;
     94   }
     95 
     96   return true;
     97 }
     98 
     99 bool RtcpMuxFilter::SetAnswer(bool answer_enable, ContentSource src) {
    100   if (state_ == ST_ACTIVE) {
    101     // Fail if we try to deactivate and no-op if we try and activate.
    102     return answer_enable;
    103   }
    104 
    105   if (!ExpectAnswer(src)) {
    106     LOG(LS_ERROR) << "Invalid state for RTCP mux answer";
    107     return false;
    108   }
    109 
    110   if (offer_enable_ && answer_enable) {
    111     state_ = ST_ACTIVE;
    112   } else if (answer_enable) {
    113     // If the offer didn't specify RTCP mux, the answer shouldn't either.
    114     LOG(LS_WARNING) << "Invalid parameters in RTCP mux answer";
    115     return false;
    116   } else {
    117     state_ = ST_INIT;
    118   }
    119   return true;
    120 }
    121 
    122 // Check the RTP payload type.  If 63 < payload type < 96, it's RTCP.
    123 // For additional details, see http://tools.ietf.org/html/rfc5761.
    124 bool IsRtcp(const char* data, int len) {
    125   if (len < 2) {
    126     return false;
    127   }
    128   char pt = data[1] & 0x7F;
    129   return (63 < pt) && (pt < 96);
    130 }
    131 
    132 bool RtcpMuxFilter::DemuxRtcp(const char* data, int len) {
    133   // If we're muxing RTP/RTCP, we must inspect each packet delivered
    134   // and determine whether it is RTP or RTCP. We do so by looking at
    135   // the RTP payload type (see IsRtcp).  Note that if we offer RTCP
    136   // mux, we may receive muxed RTCP before we receive the answer, so
    137   // we operate in that state too.
    138   bool offered_mux = ((state_ == ST_SENTOFFER) && offer_enable_);
    139   return (IsActive() || offered_mux) && IsRtcp(data, len);
    140 }
    141 
    142 bool RtcpMuxFilter::ExpectOffer(bool offer_enable, ContentSource source) {
    143   return ((state_ == ST_INIT) ||
    144           (state_ == ST_ACTIVE && offer_enable == offer_enable_) ||
    145           (state_ == ST_SENTOFFER && source == CS_LOCAL) ||
    146           (state_ == ST_RECEIVEDOFFER && source == CS_REMOTE));
    147 }
    148 
    149 bool RtcpMuxFilter::ExpectAnswer(ContentSource source) {
    150   return ((state_ == ST_SENTOFFER && source == CS_REMOTE) ||
    151           (state_ == ST_RECEIVEDOFFER && source == CS_LOCAL) ||
    152           (state_ == ST_SENTPRANSWER && source == CS_LOCAL) ||
    153           (state_ == ST_RECEIVEDPRANSWER && source == CS_REMOTE));
    154 }
    155 
    156 }  // namespace cricket
    157